LG Oven/Range Error Code F5 — Oven Relay Board Failure
What this means
The F5 error code on LG ovens indicates a failure in the relay control board (the main electronic oven control). The relay board manages power to the bake element, broil element, convection fan, and other oven functions. When it fails, the oven may not heat, may heat erratically, or may display F5 and refuse to operate. Causes include power surges, component aging, or solder joint failures on the board.
Step-by-step fix
4 stepsPower cycle the oven
Turn off the breaker for five minutes. Restore power. If F5 clears and the oven operates normally, a power surge or transient glitch may have triggered the error.
Consider adding a surge protector to the oven circuit if you experience frequent power fluctuations.
Visually inspect the relay board
Turn off the breaker. Remove the rear panel or top cover to access the main relay board. Look for obvious signs of failure: burnt components, bulging or leaking capacitors, discolored areas, or cracked solder joints around the relays.
Use a flashlight at an angle to spot hairline solder cracks that aren't visible under direct light.
Check incoming power to the board
With a multimeter, verify that the board is receiving the correct voltage from the house wiring (240V for electric ranges, 120V for gas range controls). A low or missing voltage leg can cause board errors.
If one leg of 240V is missing, the issue may be a tripped breaker, a bad outlet, or a problem in your electrical panel — not the oven.
Replace the relay control board
If the board shows visible damage or the error persists after verifying power, replace the main relay board. Photograph all wire connections before disconnecting. Install the new board, reconnect all harnesses, and test all oven functions.
Some LG boards need to be configured to your model after installation. Follow the setup instructions that come with the replacement board.
When to call a professional
Control board replacement is straightforward but misdiagnosis is common. If you're not comfortable verifying 240V power or identifying board-level faults, a technician can confirm the diagnosis before you invest in an expensive part.
Related error codes
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
Learn more about our sourcesParts you may need
Main Relay Control Board
Part #EBR74164805 · $150–$300
If board shows visible damage or error persists after reset
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